code: def backward(self, indexes, grad_outputs):
      x1, x2 = self.x1, self.x2
      cond = utils.force_array(x1 <= x2)
      ggy = chainer.functions.where(
          cond, grad_outputs[0], grad_outputs[1]
      )
      return (ggy,)
  
file_path: chainer/chainer/functions/math/minimum.py
imports: from chainer import backend
  from chainer.backends import cuda
  from chainer import function_node
  import chainer.functions
  from chainer import utils
  from chainer.utils import type_check
label_desc: Use image node_id 4 for calling the MinimumGrad obj's underlying member method code with example usage: obj.backward(indexes, grad_outputs) and returns: ggy